Arc lamp and its low-tension ignition



June 28, 1949. D. RElHlNSTElN 2,474,403

I 7 ARC LAMP AND ITS LOW-TENSION IGNITION Filed March 18, 1944 2Shets-Sheet 1 Fig. 1

9- 3 Fig. 4

Fig. 2'

Inventor:

David RtiinhinsIIeLn ATTO ll!" June 28, 1949. D. RE lCl- IINSTEIN v2,474,403

' ARC LAMP AND ITS LOW-TENSION IGNITION Filed March 18, 1944 2 SheetsSheet 2 Fig. 5

ATTORNEHS Patented June 28, 1949 ARC LAMP AND ITS LOW-TENSION IGNITIONDavid Reichinstein, Zurich, Switzerland Application March 18, 1944,Serial No. 527,053 In Switzerland October 15, 1942 Section 1, Public Law,690, August 8, 1946 Patent expires March 8, 1963 3 Claims.

The present invention refers to an arc lamp equipped with electrodes ofhigh melting point (i. e. not less than 2000 C.) arranged in fixedposition in relation to each other in a closed gasfilled space, the lampbeing of such a design that in service the radiation of light proceedsfrom the incandescent electrodes.

With a view to lowering the ignition tension of such lamps it hasalready been proposed to insert auxiliary magnesium electrodes supplyingthe pre-ionization for igniting the main electrodes.

It is further known that by means of an incandescent wire an auxiliaryarc can be initiated at lower voltage, subsequently jumping over on tothe main electrodes.

This auxiliary arc, however, involves various difficulties which havehitherto practically prevented a regular reliable service. If, forinstance, there is only a small interval betweenthe auxiliary electrodesand the main electrodes, the auxiliary electrodes will fail to functioninasmuch as their are will be extinguished as soon as the mainelectrodes begin to glow, and the auxiliary wire melt through. If, onthe other hand, the auxiliary electrodes are too far distant from thepoints of the main electrodes ignition will be unreliable. (See forreference Ediswan-P'ointolite- Lamp: Skaupy ElektrotechnischeZeitschrift 1927 vol. 48, page 1798) The present invention refers to twonew means of utilizing the Richardson efiect for lowering the ignitiontension. The first by means of a heating wire wound round the mainelectrodeswhich wire, however, is completely isolated from the mainelectrodes, and consequently does not produce an auxiliary are, merelyserving to heat the main electrodes, thus lowering their ignitionvoltage.

In the second form of the invention an auxiliary arc does form, but thisauxiliary are does not strike oil the heated electrode, but off thepoints provided there which have the characteristics of lightingconductors; by means of the device more particularly described below andbased on the principle of the competition between two arcs, thisauxiliary arc jumps over on to the two main electrodes and isautomatically extinguished.

The following description deals, with the as P sistance of the drawingsin Figs. l-4, with two constructional examples of the present invention,whilst Fig. 5 represents the system of connections making it possible toignite the lamp at low voltage.

In the arc lamp of Figure 1, the lead-in wires 2, 3, are at the sametime carriers of the electrodes l, 5, and are melted into the closedglass bulb l containing a gas which is inactive in relation to the othermaterials of which the lamp is made up. Furthermore, there are furtherlead-in wires and carrier parts i, B for the electrode heating wire 6,melted into the glass bulb i. This heating wire 6 serving as auxiliaryheating means for the electrodes is wound round the electrodes 4, 5. Asmay be seen from Fig. l, the lead-in wires 2, t for the electrodes 4, 5,are independent from the lead-in. wires l, 8 for the heating wire 6. iThe electrodes are made of metals with a high melting point, of carbon,graphite (first class conductor) or metallic oxides or silicates (secondclass conductor). The ignition of the lamp is effected by putting undervoltage the lead-in wires 2, 3 for the electrodes 4, 5, and the lead-inwires 1, 8 for the heating wire 6. The heating wire pre-heats the mainelectrodes, increases their electron emission and lowers their ignitiontension, so that shortly thereafter the ignition of the are between themain electrodes takes place, whereupon the heatng wire 6 can bedisconnected.

Figures 2 to 4 show an arc lamp provided with auxiliary heating meansadapted to generate an arc with one of the two main electrodes, whicharc then jumps over to the two main electrodes, simultaneously andautomatically discontinuing the operation of the auxiliary heatingmeans.

In the glass bulb 9 are the two main electrodes ill, I I melted on tothe lead-in wires it, ll. The heated auxiliary electrode Hi includes,however, several points l5 which have the characteristics of lightningconductors, the auxiliary arc striking ofi these points and not off theincandescent electrode It.

In order to ensure that the shortest gap shall not exist between anypart of the heating wire and the main electrodes, but between the pointsof these latter and the lightning conductors the nearest portion of theauxiliary electrode M extends transversely to the projections it, it ofmain electrodes l0, H, and the lightning conductors l5 are supported byit and extend therefrom towards the projections i2, 53 or the mainelectrodes Ill, ll.

Lastly, as regards the shapeof the main electrodes, experience has shownthat the most suitable shape is evolved by making use of the principleof the Jablotchko-ff candle, namely in providing the top of theelectrodes with a projection 12, |3-say, for example, 1 cm. inlength-the electrodes standing at a small angle in relation to eachother (Fig. 4). As to the lamp itself, the most suitable shape will bethat of a sphere, with cylinder set upon it pointing upwards; in thiscylinder the metallic dust is condensed. Jablotchkofi candle; is adevice: whichv is well known in the art and which is: described; forexample, on page 788, volume 2 of the Century Dictionary and Cyclopedia,1911 edition.

The system of connectionsior bringing about the ignition of these lampsis shown in Fig.- 5

AB is the public alternating current. supply net work of, say, 220volts. To this network is connected the primary coil I9 ofthe-transformer with the connecting terminals 25, 26. Of'the twosecondary coils and 2|, connectedtogether by means of the connection 23,the secondary; coil 21 has been designed so that it can also, be usedfor the working of the incandescent electrode 38. The connection of theterminal 22 of the second ary coil with the terminal 26 0f the primarycoil is intended to be asymbolical representation of the seriesconnection of both-- coils. 35 is an ammeter, 21, 28, 29, 39 areswitches, 3'I-a push button.

32, 33 and 34 are impedances. By closing 27', 23 and 29 the transformer.is-connected withthe network, whilstthe main electrodes 36', 3'!"receive voltage from the terminals l'8 and 24.

This voltage which inthe practical case under consideration amounts toapproximatel 640' volts is, however, not sufiicient to bring about thestriking of the are of a: lamp-Whose-inert gas, at a pressure ofapproximately-550 mm. Hg, contains a high percentage-of argon. Underthese conditions, in orderto bring about the striking of an are withouthaving recourse to an auxiliary electrode, approximately 2000". voltswould be required.

However, by causing the auxiliary electrode 38 (incandescent electrode)toglow for one moment with switch 39 closed, there-arises immediatelybetween its points and themain electrode 36* an arc which in a shorttime causes this main electrode to become incandescent, whereupon theswitch 30 is opened, the-arcjumpsover on to the other main electrode 31,and;- as soonas the latter becomes incandescent; the arc of theauxiliary electrode is automatically extinguished. In case the distancebetween the-auxiliary electrode and the main. electrodes should besomewhat greater, the impedance 34 would not'be required. Practice,however, has shownand this is the essential part of the presentinvention-that working reliability can onlybe secured-by mounting theauxiliary electrode very close to-the main electrodes so that theauxiliar arc shall never fail to strike, whilst the putting in circuitof the impedance 34, brought about by opening the switch 39, causesthe-arc to jump over on to the second main electrode and the-auxiliaryarc to become extinguished.

In the practical case-considered herethe im pedance 32 amounted toapproximately 500 ohms, and the impedance 34 to approximately 900 ohms.As to the switches, there is no necessity to work each of themseparately; on the contrary, the circuits may be closed and opened inproper sequence by means of a drum switch.

I claim:

1. In an are light radiating lamp comprising two main electrodes, aloop-shaped auxiliary electrode mounted in said lamp transversely andclose to said main electrodes to generate an auxiliary arc betweenitselfand one of said main electrodes, a single source of alternating current,a trans former having av single primary coil connected with said source,and a secondary coi1 consisting of two partial secondary non-uniformcoils interconnected in series, means connecting the entire voltage ofsaid coils of the transformer with said main electrodes, an impedance,means electrically connecting said impedance in series with saidauxiliary electrode and the smaller of the two partialssecondary coils,anda switchconnected in parallel, with said impedance, whereby the clos-111g of said switch short-circuits said impedance.

2. In an arc lamp comprising an envelope filled with an inert gas, twomain electrodes within said envelope, an auxiliar incandescent electrodemountedwithin said-envelopev close to said electrodes and adapted togenerate an auxiliary are between itself: and one of said electrodes,said main electrodes having the form of a Jablotchkoff candle, saidauxiliar electrode comprising portion extending transversely totheprojecting portions of said main electrodes, said auxiliary electrodefurther comprising pointedr portions in the nature of lightningconductors supportedby said transverse portion andextending therefromtowards said. projecting portions; and leads through said envelope tothe respective electrodes.

3. In an arc lampaccording toiclaim 2, said projecting portionsextending at a small angle in relation to each other,

DAVID RE-ICH-INSTEIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,230,004 Meikle June 12, 19171,343,200 Eschholz June 15', 1920 1,422,553 Friederich July 11, 19222,007,923 Braselton July 9, 1935 2,007,932 Ruben Jul 9, 1935 2,031,927Braselton Feb. 25, 1936 2,152,993 Friederich Apr. 4, 1939 2,177,696Ewest Oct. 31, 1939 FOREIGN PATENTS Number Country Date 188,627GreatBritain Apr. 5, 1923

